Characters: Colonies are submassive humps or are laminar with free margins. They are commonly up to 0.5 metres across. Valleys are approximately 8 millimetres wide and tend to radiate and bifurcate towards the colony margins. Septa are uniformly spaced and exsert. They form a thin ridge along the walls and plunge steeply in valley centres. There are no columellae. Tentacles are extended only at night. Colour: Distinctive uniform greenish grey-brown. Similar species: Resembles Meandrina meandrites. See also Ctenella chagius which has sinuous valleys of uniform width. Habitat: Shallow reef environments protected from strong wave action. Abundance: Usually uncommon